Electrically driven clutch actuator

Patent metadata

Field	Value
Publication number	US-11268580-B2
Application number	US-201817251574-A
Country	US
Kind code	B2
Filing date	Jun 13, 2018
Priority date	Jun 13, 2018
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

The invention relates to an electrically driven clutch actuators (1) for actuating the clutch of a transmission of a vehicle. An actuator comprises a spindle nut (11) on a spindle (9) and a pressure piece (13) displaceable relative to the spindle nut (11) and coupled to the spindle nut by a biasing spring (15). By rotation of the threaded spindle under a driving force of an electric motor (5), the spindle nut (11) compresses the biasing spring (15) and displaces the pressure piece (13) to disengage the clutch. A latching mechanism (16) is configured to limit displacement of the spindle nut away from the pressure piece under the force of the expanding biasing spring when the driving force is reduced below a predetermined level. Further, a control unit is described that reduces the driving force in response to a trigger condition to reduce power consumption in the clutch disengaged state.

First claim

The invention claimed is:

1. An electrically driven clutch actuator for actuating a clutch of a transmission of a vehicle, comprising:
a pressure piece that is axially movable between a first position and a second position corresponding to engaging and disengaging of the clutch, respectively, wherein the pressure piece is driven from the first position into the second position by a spindle drive that comprises a threaded spindle rotationally driven by an electric motor, and a spindle nut mounted on the threaded spindle and being axially displaceable by rotation of the threaded spindle;
wherein the spindle nut and the pressure piece are displaceable relative to each other in an axial direction, and are coupled to each other by a biasing spring interposed between the spindle nut and the pressure piece such that by rotation of the threaded spindle under a driving force of the electric motor, the spindle nut compresses the biasing spring and displaces the pressure piece towards the second position to disengage the clutch,
wherein when the driving force provided by the electric motor is reduced below a predetermined level, the pressure piece is returned to the first position by the restoring force of the clutch and the biasing spring expands to displace the spindle nut away from the pressure piece,
wherein a latching mechanism that is configured to limit displacement of the spindle nut away from the pressure piece under the force of the expanding biasing spring such that the biasing spring is held in a preload state, the latching mechanism comprises first latching means and second latching means, wherein the first latching means are firmly connected to the rotatable threaded spindle or the axially displaceable spindle nut.

2. The clutch actuator according to claim 1 , wherein the latching mechanism comprises a detent recess and a detent lug, wherein one of the detent recess and the detent lug is biased in the direction of engagement with the other of the detent recess and the detent lug.

3. The clutch actuator according to claim 1 , wherein the latching mechanism comprises a detent portion that is firmly connected to or provided on the threaded spindle and that has at least one detent recess, preferably more than one detent recess, on its outer circumferential surface to retain the threaded spindle in a rotational position by engagement with a detent lug.

4. The clutch actuator according to claim 1 further comprising a sensor arrangement to detect the rotational position of the threaded spindle and/or the axial position of the spindle nut and/or the axial position of the pressure piece.

5. The clutch actuator according to claim 4 , wherein the sensor arrangement includes a rotary encoder to detect rotations of the threaded spindle.

6. The clutch actuator according to claim 1 , wherein the latching mechanism is releasable by the driving force provided by the electric motor.

7. An electrically driven clutch actuator for actuating a clutch of a transmission of a vehicle, comprising:
a threaded spindle supported by one or more roller bearings and rotationally driven by an electric motor,
a spindle nut mounted on the threaded spindle and being axially displaceable by rotation of the threaded spindle from a clutch engaging position into a clutch disengaging position corresponding to engaging and disengaging of the clutch, respectively, against a restoring force of the clutch, and
a control unit for activating the electric motor to apply a driving force to the threaded spindle, wherein the control unit is configured to hold the spindle nut in the clutch disengaging position with a first value of the driving force,
wherein the control unit is configured to, when the spindle nut is held in the clutch disengaging position with the first value of the driving force, reduce the driving force in response to a trigger condition sensed by the control unit to a second value, the second value of the driving force being above a threshold value at which the spindle nut moves toward the clutch engaging position.

8. The clutch actuator according to claim 7 , wherein the control unit is configured to adjust the driving force of the electric motor.

9. The clutch actuator according to claim 7 , wherein the trigger condition is associated with predetermined driving or stationary conditions of the vehicle.

10. The clutch actuator according to claim 7 , wherein the trigger condition is a specific period of time over which the clutch remains disengaged.

11. The clutch actuator according to claim 7 , wherein the control unit is configured to perform the steps of:
1) holding the spindle nut in the clutch disengaging position with the first value of the driving force;
2) monitoring displacement of the threaded spindle or the spindle nut and gradually reducing the driving force until reaching a threshold value of the driving force at which the spindle nut begins to displace relative to the threaded spindle under the restoring force of the clutch;
3) gradually increasing the driving force above the threshold value until the spindle nut is stopped and/or returned to the clutch disengaging position.

12. The clutch actuator according to claim 11 , wherein the control unit determines the second value of the driving force of the electric motor by performing the steps 1-3 and saving the value of the driving force required for stopping and/or returning the spindle nut into the clutch disengaging position in a memory as second value for later operations of the clutch associated with the trigger condition.

13. The clutch actuator according to claim 7 , wherein a pressure piece is provided that is axially movable between a first position and a second position corresponding to engaging and disengaging of the clutch, respectively,
wherein the spindle nut and the pressure piece are displaceable relative to each other in an axial direction, and are coupled to each other by a biasing spring interposed between the spindle nut and the pressure piece such that by rotation of the threaded spindle under a driving force of the electric motor, the spindle nut compresses the biasing spring and displaces the pressure piece towards the second position to disengage the clutch.

14. The clutch actuator according to claim 13 , wherein the biasing spring is provided in a recess portion of the spindle nut and/or the pressure piece such that the spindle nut makes contact with the pressure piece when the biasing spring is compressed.

15. The clutch actuator according to claim 5 , wherein the rotary encoder is an absolute encoder to detect absolute rotations of the threaded spindle.

Assignees

• Ka Group Ag

Inventors

• Engman Jimmy

Classifications

• F16D2500/3026

  Stroke · CPC title

• F16D2500/10412

  Transmission line of a vehicle · CPC title

• F16D2500/1025

  with threaded transmission · CPC title

• F16D2500/1023

  Electric motor · CPC title

• F16D2023/123

  Clutch actuation by cams, ramps or ball-screw mechanisms · CPC title